Is there a different cord available for a gm block heater to allow it to come on before -20?

Yes, there are different cords available for GM block heaters that can enable them to operate effectively in temperatures below -20°F. These cords often include higher wattage options or specialized timers to ensure the engine block heater provides adequate warmth in extremely cold conditions. It's advisable to check with a local dealer or an automotive parts store for the appropriate cord compatible with your specific GM vehicle.